Porous refractory body impregnated with magnesium

ABSTRACT

A composition of matter useful for treating a ferrous melt to reduce sulphur content thereof comprising a compressed porous refractory body of an alkaline earth metal oxide containing a ceramic binder, said body impregnated with magnesium, the particle size of the alkaline earth metal oxide beng less than 4 mesh, said refractory body containing at least about 2 parts by weight of alkaline earth metal oxide for each part of binder and said body being impregnated with at least 35 percent by weight of magnesium, based on the total weight of the impregnated composition. This composition of matter is produced by admixing -4 mesh particles of alkaline earth metal carbonate with a binder, forming pellets of this mixture and firing the pellets to volatilize the carbon dioxide formed. The fired pellets are then immersed into molten magnesium to impregnate the pellets with magnesium metal.

United States Patent 1' Kotler et al.

1 Apr. 2, 1974 POROUS REFRACTORY BODY IMPREGNATED WITH MAGNESIUM [75]Inventors: Gerald Kotler, Hightstown; Jairaj Easwaran, Cranbury, both ofNJ.

[52] US. Cl. 75/58, 75/130 A [51] Int. Cl. C21c 7/00 [58] Field ofSearch 75/53-58, 130 A [56] References Cited UNITED STATES PATENTS2,988,445 6/1961 Hurum 75/58 2,823,989 2/1958 Deyrup.... 75/58 2,881,0687/1959 Bergh 75/53 3,393,996 7/1968 Robertsonm. 75/53 2,794,730 6/1957Perrin 75/55 3,065,070 11/1962 Otani 75/57 3,467,167 9/1969 Mahin..75/57 3,459,541 8/1969 l-lohl 75/53 3,681,050 8/1972 Ueki 75/533,314,782 4/1967 Arnaud 75/57 Primary ExaminerL. Dewayne RutledgeAssistant Examiner-Peter D. Rosenberg [5 7] ABSTRACT A composition ofmatter useful for treating a ferrous melt to reduce sulphur contentthereof comprising a compressed porous refractory body of an alkalineearth metal oxide containing a ceramic binder, said body impregnatedwith magnesium, the particle size of the alkaline earth metal oxide bengless than 4 mesh, said refractory body containing at least about 2 partsby weight of alkaline earth metal oxide for each part of binder and saidbody being impregnated with at least 35 percent by weight of magnesium,based on the total weight of the impregnated composition Thiscomposition of matter is produced by admixing -4 mesh particles ofalkaline earth metal carbonate with a binder, forming pellets of thismixture and firing the pellets to volatilize the carbon dioxide formed.The fired pellets are then immersed into molten magnesium to impregnatethe pellets with magnesium metal.

18 Claims, No Drawings BACKGROUND OF THE INVENTION In the iron and steelindustry, it is necessary to treat the ferrous base metals while in themolten state with a desulfurizing agent to reduce the sulphur content ofthe metal product. Magnesium metal is a powerful deoxidizer anddesulfurizer. However, magnesium metal boils at a low temperature andtherefore the sudden increase in volume which is produced when metallicmagnesium is added to the molten iron may result in violent explosionsas the magnesium metal is vaporized.

Various methods have been used to reduce this violent activity by slowlyintroducing the magnesium metal into molten ferrous metal under rigidlycontrolled systems. Other methods for reducing the violence is toimpregnate porous bodies with magnesium metal and to introduce thesemagnesium impregnated porous bodies into the molten ferrous metal. Underthese conditions, the impregnated magnesium metal is released at a slowenough rate that the violence is held to a minimum.

Among the known porous bodies which have been used with limited successfor this purpose are porous coke, carbon, graphite, sponge iron andceramic bodies such as quicklime, lump limestone or dolomite and thelike. I

It has been found that the porous compositions of the instant inventionpossess advantages which are not present in the prior art porous bodies.

SUMMARY OF THE INVENTION A new composition of matter has been preparedcomprising a porous refractory body of an alkaline earth metal oxidecontaining a ceramic binder, said body impregnated with magnesium, theparticle size of the alkaline earth metal oxide being less than 4 mesh,said refractory body containing at least about 2 parts by weight ofalkaline earth oxide for each part of binder, and said body impregnatedwith at least 35 percent by weight of magnesium based on the totalweight of the impregnated body. Such a product is useful fordesulfurizing ferrous melts.

Products produced by the instant invention generally contain from about30 percent to about 50 percent alkaline earth metal oxide, from about 1percent to percent binder and from about 35 percent to about 70 percentmagnesium impregnated into the pores of the product, these percentagesare based on the total weight of the impregnated body.

The porous refractory body contemplated in the instant invention isproduced by admixing a particulate alkaline earth metal carbonate and aceramic binder, pelletizing the mixture, firing the pellets to convertthe metal carbonate to metal oxide and to volatilize the carbon dioxideformed and then immersing the fired pellet in molten magnesium toimpregnate the pores of the refractory body with magnesium. The amountof alkaline earth metal carbonate employed is from about 75 percent toabout 99 percent while the amount of binder employed is from about 1percent to about percent, all of the percentages are based on the weightof the mixture.

Itis intended that the instant invention also contemplates. preparingcompositions which may fall somewhat outside the lower and upper limitsspecified above and therefore, these specified limits are merely thepreferred range of compositions and should not be construed as being theoverall limits contemplated by the instant invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS.

The porous compositions of the instant invention which are infiltratedwith magnesium are superior to the porous bodies of the prior art. Theinstant porous body not only may take up and retain magnesium in amountsgreater than about 35 percent of its total weight, but in addition,contains alkaline earth metal oxides which are useful because of theirfluxing properties.

In addition to producing a product which has all of these advantages,the porous bodies may be made with inexpensive raw material in aneconomical manner.

In preparing the porous composition of the instant invention inexpensivegranulated alkaline earth metal carbonates, such as limestone, dolomiteand similar raw materials may be used. One very inexpensive raw materialwhich may be used successfully is oolitic sands which are found innature in large quantities. Oolitic sands in general contain frompercent to percent calcium carbonate with the remainder usually beingalumina and silica. It is necessary to use a particulate alkaline earthmetal carbonate, not a massive body. If the source of thealkaline earthmetal carbonate is in a massive form, it must be crushed into aparticulate form before using.

The alkaline earth metal carbonate raw material is particulate material(or as a massive body which is pulverized) which has an average sizerange below 4 mesh. Such particulate material is thoroughly mixed with aceramic binder in amount from about 1 percent to about 25 percent byweight. Most any well-known ceramic binder may be used including clays,e.g., bentonite, water glass, Portland cement and the like. Thesebinders may be used singly or in combination with one another.

When some sands are employed, the sands themselves may containsufficient amounts of clay which will act as the binder. In such casesit may not be necessary to add the binder as a separate ingredient. Inany event however, the presence of the binder is necessary to form acohesive compressed product.

The alkaline earth metal carbonate and the binder are then mixed withsufficient water (about 2 percent to 6 percent) to form a moldableclay-like texture. This moist mixture is then pressed into pellets orbriquettes at pressures from about 1,500 psi to about 30,000 psi. Thepressed bodies are then dried preferably at to 250 C. Periods of 2 to 24hours have been found to be sufficient to remove the moisture.

The dried pressed bodies are then calcined at a temperatur from about875 C to about l,450 C for l to 10 hours. The use of temperatures whichlie somewhat below or above this specified temperature range is alsocontemplated in the instant invention. The temperature range specifiedabove merely is the preferred temperature which may be employed. Twodifferent types of products are obtained when low orhigh temperatureranges are employed. Using a lower temperature .range of about 875 C toabout l,lO C produces a product which decomposes relatively rapidlyduring the desulfurization treatment. The magnesium is released rapidly,thus increasing the rate of desulfurization. In contrast, using a hightemperature range of about l,lO0 C to about l,450 C produces arelatively more sintered product which is more mechanically stable whilethe magnesium is being released. With these two types of products it ispossible to control the rate of desulfurization within wide variations.

When the low temperature product is prepared, it is necessary to plungethe product into molten magnesium while still hot, i.e., about 750 to850 C. Periods of from about 2 to about 15 minutes have been found to beadequate to complete the infiltration. The low temperature productshould not be cooled below 700 C before introduced into the moltenmetal.

With either product, however, from about 35 percent to about 70 percentby weight of magnesium is absorbed into the pores of the calcined body,the percentage of magnesium abosrbed is based on the total weight of theinfiltrated refractory body. The molten magnesium metal penetrates intothe pores of the calcined body and remains there upon cooling.

The magnesium infiltrated refractory body when removed from the moltenmagnesium must be protected from an oxidizing atmosphere during cooling.One particularly satisfactory method is to plunge the hot refractorybody in oil during cooling. The cooled refractory body also should beprotected from the atmosphere and moisture during storage and shipping.

The ceramic porous bodies prepared in the instant invention may beimpregnated with either substantially pure magnesium or magnesiumalloys. Alloys particularly desirable to use are magnesium alloyscontaining calcium, sodium, lithium and mixtures of these metals. Theterm magnesium hereinafter referred to is meant to include magnesiummetal and alloys of magnesium metal.

ln addition to preparing pellets by placing the mixture into a mold andsubjecting the molded product to high pressure, the mixture may besubjected to extrusion and then cut into pellets.

in this extrusion method, the alkaline earth metal carbonate of 4 meshin size is mixed preferably with I from about percent to about 25percent clay and to this mixture is added from about 2 percent to about6 percent water. The mixture is then extruded through a die.

The extruded material is then cut into pellets and fired in the mannerdescribed previously.

The novel feature of the magnesium infiltrated porous structure producedin the instant invention possesses the following combined advantagesover the prior art:

1. have high porosity and therefore are capable of retaining largequantities of magnesium metal;

2. have the composition which combines the features of having alkalineearth metal oxide present for fluxing properties combined with thepresence of magnesium which is useful for desulfurizing molten ironmetal;

3. the impregnated pellets produced may be structurally strong andcapable of withstanding high temperalures. These pellets are those firedat high temperatures;

4. or the impregnated pellets produced may be very active whenintroduced into molten iron, thus capable of desulfurizing rapidly themolten iron. These pellets are those fired at the lower temperatures;

5. the magnesium infiltrated pellets made by the instant invention areuniform in composition and when they are used to desulfurize molten ironreproducible results are obtained.

It has also been discovered that when 4 mesh alkaline earth metalcarbonate is admixed with a binder and the mixture is briquetted andcalcined, the carbonate is decomposed to oxide and the carbon dioxideformed is removed leaving a porous structure of the oxide and thebinder. This porous structure remains in substantially the same size andshape as the briquetted mixture before calcination. Apparently thepresence of the binder holds the structure together as the carbonate isdecomposed to oxide. This porous structure is therefore capable ofholding large quantities of magnesium metal or alloy in its interstices.

In order to describe more fully the instant invention, the followingexamples are presented:

EXAMPLE 1 In this example, a calcium carbonate sand briquette wasprepared. The briquette contained 5.0 percent by weight of bentoniteclay.

1,682 grams of calcium carbonate sand were mixed with 84 grams ofbentonite clay. The calcium carbonate sand contained percent calciumcarbonate by weight, the remainder was silica and alumina. The averageparticle size of the sand was 60 mesh while the bentonite clay was 325mesh.

15 grams of water were added to agglomerate the mixture. The wettedmixture was placed in a cylindrical mold 1% inches in diameter and 4inches deep. A hydraulically actuated plunger was used to compress themixture at 7,500 psi for one minute. A cylindrical briquette havingdimensions of 1% inches in diameter and 2 inches in height was formed.The briquette was removed from the mold and dried in an oven for 24hours to remove the water. The briquette was then fired at l,lOO C in akiln for 3% hours to release CO thereby converting the calcium carbonateto Ca(). The briquette however, was strong enough to retain its size andshape. After calcination, the briquette weighed 49.8 gins. The averageparticle size of the calcium oxide formed in the compressed product was60 mesh.

in order to impregnate the briquette with magnesium metal, the briquettewas removed from the kiln and while still hot was immersed in a bath ofmolten magnesium at 800 C for about 1 minute. The briquette was quicklydrawn below the surface of the molten magnesium and the level ofmagnesium dropped sharply indicating infiltration of the briquette.After the briquette was removed from the molten magnesium, it wasimmediately quenched in a bath of oil to prevent oxidation. The cooledimpregnated briquette was then placed in a sealed container for storage.Upon analysis of a sample of the briquette, it was found that 45.0 gms.of magnesium had been infiltrated. This amount is equal to 47 percentmagnesium by weight of the infiltrated briquette.

in order to illustrate the use of these magnesium infiltratedcompositions, the briquettes or pellets prepared according to theprocedure described in Example 1 were produced and were added to molteniron in order to desulfurize the iron as follows:

397 lbs. of iron were melted in a furnace at 1,480 C and contained thefollowing analysis:

Carbon 3. 52 percent, Si 1.72 percent, S 0.047 percent, P 0.029 percent.A treating ladle was preheated to 1,480 C and the hot metal was tappedinto the ladle. A plunging bell assembly was preheated and 495 gms. ofthe magnesium infiltrated pellets described above were placed in thebell. A steel plate was placed under the pellets and was secured to thewalls of the bell with steel wires. The plunging temperature of themolten iron was allowed to drop to 1,400 C and the bell was plunged athigh speed into the iron. After 2% minutes, the plunging reaction wasover and the bell was raised. Spectrographic buttons were cast andanalyzed for sulfur. The sulfur content was found to be .10 percent. Theretained magnesium in the iron was 0.020 percent.

The desulfurization efficicncy was 81 percent while the efficicncy ofmagnesium utilization was 22 percent.

It has been found that the time of immersion of the porous refractorybody in the molten iron preferably should be from 1 to minutes todesulfurize the molten iron.

EXAMPLE 2 In this example another calcium carbonate sand briquette wasprepared. The briquette contained 2.35 percent by weight of bentoniteclay.

1,682 grams of calcium carbonate sand were mixed with 38 grams ofbentonite clay. The calcium carbonate sand and the bentonite clay werethe same as those described in the previous example.

grams of water were added to agglomerate the mixture and pellets weremade in the same manner as those described above except that a pressureof 1500 psi was used instead of 7,500 psi. The pellets were fired at 900C in a kiln for 3% hours to release CO thereby converting calciumcarbonate to CaO. The briquette, however, was strong enough to retainits size and shape. After calcination the briquette weighed 40 gms.

The briquette was impregnated with magnesium metal in the same manner asthat described in Example 1. The impregnated briquette was weighed andit was found that 45 gms of magnesium had been impregnated. This amountis equal to 53 percent magnesium by weight of the infiltrated briquette.

When the briquette was used to desulfurize molten iron, the infiltratedmagnesium was released more rapidly than that obtained in Example 1. Theextent of desulfurization however, was substantially the same.

EXAMPLE 3 The procedure of Example 2 was followed except that a pressureof 7,500 psi was used to compress the sand mixture instead of 1,500 psi.

After weighing, it was found that 52.4 gms of magnesium (54 percent) hadbeen infiltrated into a briquette that weighed 45.2 gms aftercalcination.

In addition to the process described above in which a particulatealkaline earth metal carbonate material is mixed with a ceramic binder,it has been found desirable to add in addition to the alkaline earthmetal carbonate and the binder, a finely divided cellulosic mate rialsuch as sawdust, corn cob grits, corn stalks, oat hulls and the likewhich have been ground to mesh.

The addition of this cellulosic material produces a product which ismore porous than the previous product and therefore the product is ableto absorb more molten magnesium.

When the cellulosic material is employed. the alkaline earth metalcarbonate should be present in the mixture in amount from 55 percent topercent, the binder present in amount from 1 percent to 15 percent andthe cellulosic material in amount from 10 percent to 30 percent.

The following example illustrates the preparation of calcium oxidepellets which are prepared by admixing calcium carbonate, a binder and acellulosic material and calcining the mixture to form the product.

EXAMPLE 4 This example illustrates the preparation of a calciumcarbonate sand briquette which contains 2.4 percent by weight ofbentonite clay and ll percent by weight of sawdust.

788 gms of calcium carbonate sand as used in Example 2 was hand mixedwith 38 gms of 325 mesh bentonite clay and 110 gms of 100 mesh sawdust.The procedure of Example 1 was followed to produce the briquette.

After weighing the briquette, it was found that 27.9 gms of magnesium(66 percent) metal had been infiltrated into the briquette. Theinfiltrated briquette weighed 14.6 gms after calcination.

EXAMPLE 5 This example illustrates an extrusion process for theproduction of magnesium infiltratable pellets comprising percent calciumcarbonate sand, 10 percent Tennessee ball clay and 5 percent bentoniteclay.

85 lbs. of calcium carbonate sand, 10 lbs. of Tennessee ball clay, 5lbs. of bentonite clay and 0.5 lb. of corn starch were mixed togetherwith a slight amount of water to form a paste. This mixture was fed intothe hopper of a Chamber Bros. laboratory extruding machine. The mixturewas extruded into a cylindrically shaped briquette 1% inches in diameterand approximately 4 inches long. The briquette was then cut into four 1inch pellets such that each pellet measured approximately 1 inch long X1% inches in diameter. The pellets were dried at 120 C for about 24hours and then calcined at 1,370 C for 5 hours. While the pellets werestill hot (426 C) they were immersed in a bath of molten magnesium andinfiltrated. It was found that an average of 44 percent by weight ofmagnesium was infiltrated into the pellets.

EXAMPLE 6 This example illustrates the use of water glass (Na SiO 2H O)as a ceramic binder instead of bentonite clay as given in Example 1.

The procedure of Example 1 was followed using 1 percent water glassinstead of 5 percent bentonite clay as a binder. gms of oolitic sandwere mixed with 1 gm of water glass. The mixture was formed into abriquette and the briquette was calcined at l,l00 C. The fired briquetteweighed 66.9 gms after calcination. The briquette was then immersed inmolten magnesium metal and the briquette weighed 133.4 gms afterinfiltration. After infiltration, it was found that 49.9 percentmagnesium had been infiltrated into the briquette.

EXAMPLES 7 8 These examples illustrate the production of calciumcarbonate sand briquettes containing 5 percent benton- 2. Compositionaccording to claim 1 in which there are from about 2 to about 50 partsby weight of the alkaline earth metal oxide for each part of binder.

3. Composition according to claim 1 in which the alite clay infiltratedwith alloys of magnesium. 5

The procedure of Example 1 was followed except kalme earth Petal i f 19that two alloys of magnesium in the molten state were Composltloaccording 9 F w whlch the P used to infiltrate two separate briquettesinstead of submus refractory qy PQ impregnated stantiaily pure magnesiumas in Example 1. The first an alloy of gnc alloy was a M g-Ca alloycontaining 5 percent calcium to 5- A porous compressed refractory bodycomposition and the remainer magnesium; the second was a comprising aporous structure of an alkaline earth M (j ,i allgys containing 5percent l i 2 metal oxide and a ceramic binder, said binder selectedcent lithium and the remainder magnesium. After from the groupconsisting of clay, Wat glass, Cement weighing the briquettes before andafter infiltration in an mix r h re i r re containing magnethese alloys,it was found that 59.0 percent by weight sium absorbed in theinterstices of said porous strucof the Mg-Ca alloy had been infiltratedinto the first ture, the alkaline earth metal Oxide having an agebriquette and 59.6 percent of the Mg-Ca-Li alloy had particle size below4 mesh, the amount of said alkaline been infiltrated into the second b itt earth metal oxide being present in amount from about Both of thesealloy infiltrated briquettes were useful 30 Percent I0 abOUI 50 P Saidbinder being presin desulfurizing a molten iron lt, ent in amount fromabout 1 percent to about 15 per- The operational details and the resultsobtained of all cent and said composition being impregnated with at ofthese examples are recorded in the following table. least about 35percent magnesium absorbed in said it should be noted that all of thesebriquettes were instructure, all of the percentages expressed on aweight filtrated with an amount of magnesium or magnesium basis. alloysfrom 44 percent to 66 percent. All of these infil- 6. A process forproducing a porous, compressed retrated briquettes are useful for'desulfurizing molten fractory body comprising a porous structure of analkametal in an efficient manner without forming a violent line earthmetal oxide and a ceramic binder, said binder reaction. selected fromthe group consisting of ciay, water, glass, While this invention hasbeen described and illuscement and mixtures thereof, said structurecontaining trated by the examples shown, it is not intended to bemagnesium absorbed in the interstices of said porous strictly limitedthereto, and other variations and modistructure, said process whichcomprises admixing a fications may be employed within the scope of thefolparticulate alkaline earth metal carbonate and a celowing claims.ramic binder, the amount of said alkaline earth metal TABLE PRIOR TOCALCINATION BRlQUETTING CALCINING MAG. EXAM LE crrco SAND BINDER BINDERPRESSURE TEMPERATURE INFILTRATED i 95.0% Bcntonile 5.0% 7500 psi ll00C47% 2 97.65% Bcntonite 2.35% 1500 psi 900C 53% 3 97.65% Bcntonilc 2.35%7500 psi 900C 52.4% 4 86.6% Bentonitc 2.40% 1500 psi 900C 66% & Sawdust11.0% S 85.0% Tennessee 10% l370C 44% Ball Clay Bcntonite 5% Corn Starch0.5% a 95.0% Water (miss 1% 7500 psi 1 100C 49.9%

Mg-Cn ALLOY lNFiLTRA'll-Il) 7 95.0% Bentonitc 5% 7500 psi 1 100C 59.0%

Mg-Ca-Li ALLOY lNFlLTRATliD a 95.0% Bcntonitc 5% 7500 psi 1100C- 59.6%

We claim: 55 carbonate being present in amount from about 75 per- 1. Aporous compressed refractory body composi n cent to about 99 percent,said ceramic binder being comprising a porous structure of an alkalineearth present in amount from about 1 percent to about 25 metal oxide anda ceramic binder, said binder selected percent, all of the percentagesexpressed on a weight fmm the g p consisting 0f clay, Water g Cementbasis, forming pellets of said mixture, drying and firing and mixturesthereof, Said tur ntaining magnesaid pellets at a temperature sufficientto convert the sium absorbed in interstices of said porous structure,metal carbonate to metal oxide and to volatilize the said refractorybody composition having at least about carbon dioxide formed, thusforming a porous, com- 2 parts by weight of alkaline earth metal oxidepresent pressed structure of a ceramic body, and impregnating in saidcomposition for each part of binder, said alkathe pores of said bodywith magnesium. line earth metal oxide having an average particle size7. A process for producing a porous, compressed rebelow 4 mesh, and saidcomposition being impregnated with at least 35 percent by weight ofmagnesium absorbed in said structure based on the total weight of theimpregnated composition.

fractory body comprising a porous structure of an alkaline earth metaloxide and a ceramic binder, said binder selected from the groupconsisting of clay, water glass, cement and mixtures thereof, saidstructure containing magnesium absorbed in the interstices of saidporous structure, said process which comprises admixing a particulatealkaline earth metal carbonate and a ceramic binder, said alkaline earthmetal carbonate being present in amount from about 75 percent to about99 percent, said ceramic binder being present in amount from about 1percent to about 25 percent, all of the percentages expressed on aweight basis, adding to said mixture sufficient water to form a moldablemixture, forming pellets from said mixture, drying and firing saidpellets at a temperature from about 875 C to about 1,450 C to convertthe metal carbonate to metal oxide and to volatilize the carbon dioxideformed, thus forming a porous, compressed and open structure of aceramic body, immersing said body with magnesium and removing saidimpregnated body from said molten metal.

8. Process according to claim 7 in which the moldable mixture iscompressed at a pressure from about 1,500 psi to about 30,000 psi toform pellets.

9. Process according to claim 7 in which the moldable mixture isextruded to form pellets.

10. Process according to claim 7 in which the alkaline earth metalcarbonate is calcium carbonate.

11. Process according to claim 7 in which the alkaline earth metalcarbonate is of a size of -4 mesh.

12. A process for producing a porous, refractory body comprising aporous structure of an alkaline earth metal oxide and a ceramic binder,said binder selected from the group consisting of clay, water glass,cement and mixtures thereof, said structure containing magnesiumabsorbed in the interstices of said porous structure, said process whichcomprises admixing a particulate alkaline earth metal carbonate, aceramic binder and a cellulosic material, the amount of said alkalineearth metal carbonate being present in amount from about 55 percent toabout 70 percent, said cellulosic material being present in amount from10 percent to 30 percent, all of the percentages expressed on a weightbasis, adding to said mixture from about 2 percent to about 6 percentwater to form a moldable mixture, forming pellets from said mixture,drying and firing said pellets at a temperature from about 875 C toabout l,450 C to volatilize the carbon dioxide formed and to burn offthe cellulosic material, thus forming pellets of a porous ceramic bodyhaving an open structure comprising said alkaline earth metal oxide andsaid binder, immersing said body in molten magnesium metal to fill thepores of said structure with magnesium and removing said impregnatedbody from said molten metal.

13. Process according to claim 12 in which the size of the cellulosicmaterial employed is 20 mesh.

14. Process according to claim 12 in which the cellulosic material isselected from the group consisting of sawdust, corn cob grits, cornstalks and oat hulls, and mixtures thereof.

15. A process for treating molten iron which comprises immersing aporous structure comprising a refractory body composition impregnatedwith magnesium into said molten iron to reduce the sulfur contentthereof, the porous refractory body composition comprising an alkalineearth metal oxide and a ceramic binder, said binder selected from thegroup consisting of clay, water glass, cement and mixtures thereof, saidrefractory binder having from about 2 to about 50 parts by weight ofalkaline earth metal oxide for each part of binder, the alkaline earthmetal oxide present in said composition having an average particle sizebelow 4 mesh, and said composition being impregnated into the pores ofsaid structure with at least about 35 percent by weight of magnesium.

16. A process for treating molten iron which comprises immersing aporous structure comprising a refractory body impregnated with magnesiuminto said molten iron to reduce the sulfur content thereof, said porousrefractory body comprising from about 30 percent to about 50 percentalkaline earth metal oxide, from about 1 percent to about 15 percent ofa ceramic binder, said binder selected from the group consisting ofclay, water glass, cement and mixtures thereof, and

said body impregnated into the pores of said structure with from about35 percent to about percent magnesium, all of the percentages expressedon a weight ba sis.

17. Process according to claim 16 in which the magnesium employed is amagnesium alloy.

18. A process for desulfurizing molten iron which comprises immersing aporous structure comprising a refractory body impregnated with magnesiuminto said molten iron for a period of about 1 to about 10 minutes andremoving said body from said molten iron after said period, saidrefractory body comprising from about 30 percent to about 50 percentalkaline earth metal oxide, from about 1 percent to about 15 percent ofa ceramic binder, said binder selected from the group consisting ofclay, water glass, cement and mixtures thereof, and said bodyimpregnated into the pores of said structure with from about 35 percentto about 70 percent magnesium, all of the percentages expressed on aweight basis.

2. Composition according to claim 1 in which there are from about 2 toabout 50 parts by weight of the alkaline earth metal oxide for each partof binder.
 3. Composition according to claim 1 in which the alkalineearth metal oxide is calcium oxide.
 4. Composition according to claim 1in which the porous refractory body composition is impregnated with analloy of magnesium.
 5. A porous compressed refractory body compositioncomprising a porous structure of an alkaline earth metal oxide and aceramic binder, said binder selected from the group consisting of clay,water glass, cement and mixtures thereof, said structure containingmagnesium absorbed in the interstices of said porous structure, thealkaline earth metal oxide having an average particle size below 4 mesh,the amount of said alkaline earth metal oxide being present in amountfrom about 30 percent to about 50 percent, said binder being present inamount from about 1 percent to about 15 percent and said compositionbeing impregnated with at least about 35 percent magnesium absorbed insaid structure, all of the percentages expressed on a weight basis.
 6. Aprocess for producing a porous, compressed refractory body comprising aporous structure of an alkaline earth metal oxide and a ceramic binder,said binder selected from the group consisting of clay, water, glass,cement and mixtures thereof, said structure containing magnesiumabsorbed in the interstices of said porous structure, said process whichcomprises admixing a particulate alkaline earth metal carbonate and aceramic binder, the amount of said alkaline earth metal carbonate beingpresent in amount from about 75 percent to about 99 percent, saidceramic binder being present in amount from about 1 percent to about 25percent, all of the percentages expressed on a weight basis, formingpellets of said mixture, drying and firing said pellets at a temperaturesufficient to convert the metal carbonate to metal oxide and tovolatilize the carbon dioxide formed, thus forming a porous, compressedstructure of a ceramic body, and impregnating the pores of said bodywith magnesium.
 7. A process for producing a porous, compressedrefractory body comprising a porous structure of an alkaline earth metaloxide and a ceramic binder, said binder selected from the groupconsisting of clay, water glass, cement and mixtures thereof, saidstructure containing magnesium absorbed in the interstices of saidporous structure, said process which comprises admixing a particulatealkaline earth metal carbonate and a ceramic binder, said alkaline earthmetal carbonate being present in amount from about 75 percent to about99 percent, said ceramic binder being present in amount from about 1percent to about 25 percent, all of the percentages expressed on aweight basis, adding to said mixture sufficient water to form a moldablemixture, forming pellets from said mixture, drying and firing saidpellets at a temperature from about 875* C to about 1,450* C to convertthe metal carbonate to metal oxide and to volatilize the carbon dioxideformed, thus forming a porous, compressed and open structure of aceramic body, immersing said body with magnesium and removing saidimpregnated body from said molten metal.
 8. Process according to claim 7in which the moldable mixture is compressed at a pressure from about1,500 psi to about 30,000 psi to form pellets.
 9. Process according toclaim 7 in which the moldable mixture is extruded to form pellets. 10.Process according to claim 7 in which the alkaline earth metal carbonateis calcium carbonate.
 11. Process according to claim 7 in which thealkaline earth metal carbonate is of a size of -4 mesh.
 12. A processfor producing a porous, refractory body comprising a porous structure ofan alkaline earth metal oxide and a ceramic binder, said binder selectedfrom the group consisting of clay, water glass, cement and mixturesthereof, said structure containing magnesium absorbed in the intersticesof said porous structure, said process which comprises admixing aparticulate alkaline earth metal carbonate, a ceramic binder and acellulosic material, the amount of said alkaline earth metal carbonatebeing present in amount from about 55 percent to about 70 percent, saidcellulosic material being present in amount from 10 percent to 30percent, all of the percentages expressed on a weight basis, adding tosaid mixture from about 2 percent to about 6 percent water to form amoldable mixture, forming pellets from said mixture, drying and firingsaid pellets at a temperature from about 875* C to about 1,450* C tovolatilize the carbon dioxide formed and to burn off the cellulosicmaterial, thus forming pellets of a porous ceramic body having an openstructure comprising said alkaline earth metal oxide and said binder,immersing said body in molten magnesium metal to fill the pores of saidstructure with magnesium and removing said impregnated body from saidmolten metal.
 13. Process according to claim 12 in which the size of thecellulosic material employed is -20 mesh.
 14. Process according to claim12 in which the cellulosic material is selected from the groupconsisting of sawdust, corn cob grits, corn stalks and oat hulls, andmixtures thereof.
 15. A process for treating molten iron which comprisesimmersing a porous structure comprising a refractory body compositionimpregnated with magnesium into said molten iron to reduce the sulfurcontent thereof, the porous refractory body composition comprising analkaline earth metal oxide and a ceramic binder, said binder selectedfrom the group consisting of clay, water glass, cement and mixturesthereof, said refractory binder having from about 2 to about 50 parts byweight of alkaline earth metal oxide for each part of binder, thealkaline earth metal oxide present in said composition having an averageparticle size below 4 mesh, and said composition being impregnated intothe pores of said structure with at least about 35 percent by weight ofmagnesium.
 16. A process for treating molten iron which comprisesimmersing a porous structure comprising a refractory body impregnatedwith magnesium into said molten iron to reduce the sulfur contentthereof, said porous refractory body comprising from about 30 percent toabout 50 percent alkaline earth metal oxide, from about 1 percent toabout 15 percent of a ceramic binder, said binder selected from thegroup consisting of clay, water glass, cement and mixtures thereof, andsAid body impregnated into the pores of said structure with from about35 percent to about 70 percent magnesium, all of the percentagesexpressed on a weight basis.
 17. Process according to claim 16 in whichthe magnesium employed is a magnesium alloy.
 18. A process fordesulfurizing molten iron which comprises immersing a porous structurecomprising a refractory body impregnated with magnesium into said molteniron for a period of about 1 to about 10 minutes and removing said bodyfrom said molten iron after said period, said refractory body comprisingfrom about 30 percent to about 50 percent alkaline earth metal oxide,from about 1 percent to about 15 percent of a ceramic binder, saidbinder selected from the group consisting of clay, water glass, cementand mixtures thereof, and said body impregnated into the pores of saidstructure with from about 35 percent to about 70 percent magnesium, allof the percentages expressed on a weight basis.